U.S. patent application number 12/424299 was filed with the patent office on 2009-12-03 for organic light emitting display and method of driving the same.
Invention is credited to Sang-Moo Choi, Wang-Jo Lee.
Application Number | 20090295782 12/424299 |
Document ID | / |
Family ID | 41379214 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090295782 |
Kind Code |
A1 |
Lee; Wang-Jo ; et
al. |
December 3, 2009 |
ORGANIC LIGHT EMITTING DISPLAY AND METHOD OF DRIVING THE SAME
Abstract
An organic light emitting display and a driving method thereof
that reduces false contour noise and the occurrence of a stripe
pattern generated in a digital driving manner. The organic light
emitting display includes a scan driver for supplying a scan signal
to scan lines, a data driver for supplying a data signal to data
lines, and pixels coupled to the scan lines and the data lines.
Each of the pixels includes an organic light emitting diode. The
organic light emitting diodes of the pixels coupled to a scan line
are alternately positioned in a first horizontal line and a second
horizontal line adjacent to the first horizontal line,
respectively.
Inventors: |
Lee; Wang-Jo; (Suwon-si,
KR) ; Choi; Sang-Moo; (Suwon-si, KR) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
41379214 |
Appl. No.: |
12/424299 |
Filed: |
April 15, 2009 |
Current U.S.
Class: |
345/213 ;
345/82 |
Current CPC
Class: |
G09G 3/3258 20130101;
G09G 2310/0218 20130101; G09G 2300/0842 20130101; G09G 2320/0261
20130101; G09G 2320/0266 20130101; G09G 2300/0452 20130101; G09G
2310/0224 20130101; G09G 3/204 20130101; G09G 3/2022 20130101 |
Class at
Publication: |
345/213 ;
345/82 |
International
Class: |
G06F 3/038 20060101
G06F003/038 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2008 |
KR |
10-2008-0049709 |
Claims
1. An organic light emitting display comprising: a scan driver for
supplying a scan signal to scan lines; a data driver for supplying
a data signal to data lines; and pixels coupled to the scan lines
and the data lines, each of the pixels having corresponding organic
light emitting diodes (OLEDs), wherein the organic light emitting
diodes of first pixels and second pixels of said pixels coupled to
a scan line of the scan lines are alternately positioned in a first
horizontal line and a second horizontal line adjacent to the first
horizontal line, respectively.
2. The organic light emitting display as claimed in claim 1,
wherein, the data driver is configured to supply the data signal
corresponding to the first horizontal line to corresponding data
lines of the data lines coupled to the first pixels, and supply the
data signal corresponding to the second horizontal line to
corresponding data lines of the data lines coupled to the second
pixels when the scan signal is supplied to the scan line.
3. The organic light emitting display as claimed in claim 2,
further comprising a timing controller for rearranging received
data and supplying the rearranged data to the data driver so that
the data signal corresponding to the first horizontal line and the
data signal corresponding to the second horizontal line are
supplied from the data driver in accordance with the rearranged
data.
4. The organic light emitting display as claimed in claim 2,
wherein the data signal is a first data signal with which the
pixels emit light or a second data signal with which the pixels do
not emit light.
5. The organic light emitting display as claimed in claim 1,
wherein a source/drain metal of a driving transistor included in
each of the first pixels for supplying a current to a corresponding
one of the organic light emitting diodes is electrically coupled to
an anode electrode of the organic light emitting diode positioned
in the first horizontal line through a contact hole.
6. The organic light emitting display as claimed in claim 1,
wherein each of the pixels comprises a red sub-pixel having a red
organic light emitting diode among the OLEDs, a green sub-pixel
having a green organic light emitting diode among the OLEDs, and a
blue sub-pixel having a blue organic light emitting diode among the
OLEDs.
7. The organic light emitting display as claimed in claim 1,
wherein the scan lines comprise odd-numbered scan lines and
even-numbered scan lines, which are driven at a time difference of
1/2 frame.
8. A method of driving an organic light emitting display having
pixels coupled to data lines and scan lines, each of the pixels
having an organic light emitting diode, the method comprising:
while supplying a scan signal to a scan line of the scan lines,
supplying a data signal to first pixels of the pixels that are
coupled to the scan line and have their organic light emitting
diodes (OLEDs) positioned on a first horizontal line; and while
supplying the scan signal to the scan line, supplying another data
signal to second pixels of the pixels that are coupled to the scan
line and have their OLEDs positioned on a second horizontal line
adjacent to the first horizontal line.
9. The method as claimed in claim 8, wherein the OLEDs of the first
pixels and the OLEDs of the second pixels are alternately arranged
between the first horizontal line and the second horizontal
line.
10. The method as claimed in claim 9, wherein the data signal is a
first data signal with which the pixels emit light or a second data
signal with which the pixels do not emit light.
11. The method as claimed in claim 8, wherein each of the pixels
comprises a red sub-pixel having a red organic light emitting
diode, a green sub-pixel having a green organic light emitting
diode, and a blue sub-pixel having a blue organic light emitting
diode.
12. The method as claimed in claim 8, wherein one frame is divided
into a plurality of sub-frames, and the scan lines comprise
odd-numbered scan lines and even-numbered scan lines, which are
driven at a time difference of 1/2 frame.
13. A method of driving an organic light emitting display having a
plurality of pixels coupled to a scan line and a data line, the
method comprising: supplying a scan signal to the scan line;
supplying a first data signal to a first pixel of the pixels, the
first pixel having at least one first organic light emitting diode
positioned on a first horizontal line; and supplying a second data
signal to a second pixel of the pixels, the second pixel having at
least one second organic light emitting diode positioned on a
second horizontal line adjacent to the first horizontal line.
14. The method of claim 13, wherein a pixel of the plurality of
pixels comprises sub-pixels, and each of the sub-pixels has an
organic light emitting diode positioned on a same horizontal line.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2008-0049709, filed on May 28,
2008, in the Korean Intellectual Property Office, the entire
content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an organic light emitting
display and a method of driving the same.
[0004] 2. Description of Related Art
[0005] Recently, there have been various types of flat panel
display devices with reduced weight and volume in comparison to
cathode ray tube display devices. The flat panel display devices
can be categorized as a liquid crystal display, a field emission
display, a plasma display panel, an organic light emitting display,
and the like.
[0006] Among these flat panel display devices, the organic light
emitting display displays images using organic light emitting
diodes (OLEDs) that emit light through the recombination of
electrons and holes. The organic light emitting display device has
a fast response speed and a low power consumption.
[0007] Generally, pixels of an organic light emitting display
device display images by charging a predetermined voltage in a
storage capacitor included in each of the pixels and supplying a
current corresponding to the charged voltage to an OLED (an analog
driving manner). However, in such a driving method (or manner),
there is a limit to the number of gray levels because expressing a
large number of gray levels requires the use of a large number of
different voltages stored in the storage capacitor. Further, it is
difficult to display a uniform image due to variations on the
threshold voltage and mobility of a driving transistor included in
each of the pixels.
[0008] In order to solve these problems, there has been proposed a
digital driving manner. In the digital driving manner, a data
signal corresponding to turn-on or turn-off is supplied to each
pixel, and turn-on times of the pixels are controlled during a
plurality of sub-frame periods included in one frame, thereby
expressing a gray level. However, in the digital driving manner, a
gray level is expressed according to a light emitting time of the
pixels. For this reason, false contour noise is generated while a
moving image is displayed.
[0009] In order to reduce such false contour noise, a method of
driving even-numbered and odd-numbered scan lines at a time
difference of 1/2 frame has been proposed in Korean Patent
Application No. 2006-0110571. In Korean Patent Application No.
2006-0110571, when pixels coupled to the even-numbered scan lines
are driven, pixels coupled to the odd-numbered scan lines are then
driven after 1/2 frame. As such, if the pixels coupled to the
even-numbered and odd-numbered scan lines are driven at a time
difference of 1/2 frame, images having different weight values are
displayed between adjacent lines. Accordingly, false contour noise
can be reduced without an increase in number of sub-frames.
[0010] However, when the pixels coupled to the even-numbered and
odd-numbered scan lines are driven at a time difference of 1/2
frame, line-shaped noise may be additionally generated.
SUMMARY OF THE INVENTION
[0011] Accordingly, it is an aspect of the present invention to
provide an organic light emitting display and a method of driving
the same that reduces false contour noise and the occurrence of a
stripe generated in a digital driving manner.
[0012] According to an embodiment of the present invention, an
organic light emitting display includes: a scan driver for
supplying a scan signal to scan lines; a data driver for supplying
a data signal to data lines; and pixels coupled to the scan lines
and the data lines. Each of the pixels has corresponding organic
light emitting diodes. The organic light emitting diodes of first
pixels and second pixels of said pixels coupled to a scan line of
the scan lines are alternately positioned in a first horizontal
line and a second horizontal line adjacent to the first horizontal
line, respectively.
[0013] The data driver may be configured to supply the data signal
corresponding to the first horizontal line to corresponding data
lines of the data lines coupled to the first pixels, and may supply
the data signal corresponding to the second horizontal line to
corresponding data lines of the data lines coupled to the second
pixels when the scan signal is supplied to the scan line. The data
signal may be a first data signal with which the pixels emit light
or a second data signal with which the pixels do not emit light. A
source/drain metal of a driving transistor included in each of the
first pixels for supplying a current to a corresponding one of the
organic light emitting diodes may be electrically coupled to an
anode electrode of the organic light emitting diode positioned on
the first horizontal line through a contact hole. The organic light
emitting display may further include a timing controller for
rearranging received data and supplying the rearranged data to the
data driver so that the data signal corresponding to the first
horizontal line and the data signal corresponding to the second
horizontal line are supplied from the data driver in accordance
with the rearranged data. The scan lines may include odd-numbered
scan lines and even-numbered scan lines, which are driven at a time
difference of 1/2 frame.
[0014] According to another embodiment of the present invention, a
driving method of an organic light emitting display is provided.
The display has pixels coupled to data lines and scan lines, and
each of the pixels includes at least one organic light emitting
diode. The method includes: while supplying a scan signal to a scan
line of the scan lines, supplying a data signal to first pixels of
the pixels that are coupled to the scan line and have their organic
light emitting diodes positioned on a first horizontal line; and
while supplying the scan signal to the scan line, supplying another
data signal to second pixels of the pixels that are coupled to the
scan line and have their organic light emitting diodes positioned
on a second horizontal line.
[0015] The organic light emitting diodes of the first pixels and
the organic light emitting diodes of the second pixels may be
alternately arranged between the first horizontal line and the
second horizontal line. The data signal may be a first data signal
with which the pixels emit light or a second data signal with which
the pixels do not emit light. One frame may be divided into a
plurality of sub-frames, and the scan lines may include
odd-numbered scan lines and even-numbered scan lines, which are
driven at a time difference of 1/2 frame.
[0016] According to an embodiment of the present invention, an
organic light emitting display includes: a plurality of scan lines
having odd-numbered scan lines and even-numbered scan lines
configured to be driven at a time difference of 1/2 frame; and a
plurality of pixels coupled to a scan line of the plurality of scan
lines, first pixels of the plurality of pixels having first organic
light emitting diodes positioned on a first horizontal line and
second pixels of the plurality of pixels having second organic
light emitting diodes positioned on a second horizontal line
adjacent to the first horizontal line.
[0017] The first organic light emitting diodes and the second
organic light emitting diodes may be alternately arranged between
the first horizontal line and the second horizontal line. A pixel
of the plurality of pixels may include sub-pixels, and each of the
sub-pixels may have an organic light emitting diode positioned on a
same horizontal line.
[0018] According to an embodiment of the present invention, a
method is provided for driving an organic light emitting display
having a plurality of pixels coupled to a scan line and a data
line. The method includes: supplying a scan signal to the scan
line; supplying a first data signal to a first pixel of the pixels,
the first pixel having an organic light emitting diode positioned
on a first horizontal line; and supplying a second data signal to a
second pixel of the pixels, the second pixel having another organic
light emitting diode positioned on a second horizontal line
adjacent to the first horizontal line. A pixel of the plurality of
pixels may include sub-pixels, and each of the sub-pixels may have
an organic light emitting diode positioned on a same horizontal
line.
[0019] In an organic light emitting display and a driving method
thereof according to embodiments of the present invention, when
even-numbered and odd-numbered scan lines are driven at a time
difference of 1/2 frame, pixels emit light in a mosaic form, and
therefore, line-shaped noise can be prevented or reduced. Further,
if the pixels emit light in a mosaic form, false contour noise can
be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings, together with the specification,
illustrate exemplary embodiments of the present invention, and,
together with the description, serve to explain the principles of
the present invention.
[0021] FIG. 1 shows a schematic block diagram of an organic light
emitting display according to an embodiment of the present
invention.
[0022] FIG. 2 shows a schematic circuit diagram of pixels shown in
FIG. 1 in detail.
[0023] FIGS. 3A and 3B are waveform diagrams illustrating a method
of driving the organic light emitting display of FIG. 1.
[0024] FIGS. 4A and 4B are drawings that show pixels emitting light
in a mosaic form by the driving waveforms of FIGS. 3A and 3B,
respectively.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0025] Hereinafter, certain exemplary embodiments according to the
present invention will be described with reference to the
accompanying drawings. Here, when a first element is described as
being coupled to a second element, the first element may be
directly coupled to the second element or may be indirectly coupled
to the second element via a third element. Further, some of the
elements that are not essential to a complete understanding of the
present invention are omitted for clarity. Also, like reference
numerals refer to like elements throughout.
[0026] FIG. 1 shows an organic light emitting display according to
an embodiment of the present invention.
[0027] Referring to FIG. 1, the organic light emitting display
according to the embodiment of the present invention includes a
display unit 30 including pixels 40 positioned at crossing portions
of scan lines S0 to Sn and data lines D1 to Dm; a scan driver 10
for driving the scan lines S0 to Sn; a data driver 20 for driving
the data lines D1 to Dm; and a timing controller 50 for controlling
the scan driver 10 and the data driver 20.
[0028] The display unit 30 supplies a first power ELVDD and a
second power ELVSS, supplied from the outside, to the pixels 40.
The pixels 40, to which the first power ELVDD and the second power
ELVSS are supplied, display an image (e.g., a predetermined image)
while emitting or not emitting light in response to a data
signal.
[0029] Here, each of the pixels 40 includes a red sub-pixel R, a
green sub-pixel G and a blue sub-pixel B. The red sub-pixel R
includes a red organic light emitting diode OLED(R) for emitting
red light and a pixel circuit 42 for controlling whether or not a
current is supplied to the red organic light emitting diode
OLED(R). The green sub-pixel G includes a green organic light
emitting diode OLED(G) for emitting green light and a pixel circuit
42 for controlling whether or not a current is supplied to the
green organic light emitting diode OLED(G). The blue sub-pixel B
includes a blue organic light emitting diode OLED(B) for emitting
blue light and a pixel circuit 42 for controlling whether or not a
current is supplied to the blue organic light emitting diode
OLED(B).
[0030] In an embodiment of the present invention, pixels 40 coupled
to the same scan line S (e.g., S0 to Sn) are arranged so that their
organic light emitting diodes OLEDs are alternately positioned on
different horizontal lines. More specifically, organic light
emitting diodes OLEDs of some pixels 40 coupled to an i-th (i is a
natural number) scan line Si are arranged in an (i+1)-th horizontal
line, and organic light emitting diodes OLEDs of the other pixels
40 alternately arranged with the some pixels 40 are arranged in an
i-th horizontal line.
[0031] For example, in FIG. 1, organic light emitting diodes
OLED(R), OLED(G) and OLED(B) of sub-pixels R, G and B included in a
pixel 40 coupled to the first scan line S1 and the first to third
data lines D1 to D3 are positioned on the (i+1)-th horizontal line.
Organic light emitting diodes OLED(R), OLED(G) and OLED(B) of
sub-pixels R, G and B included in a pixel 40 coupled to the first
scan line S1 and the fourth to sixth data lines D4 to D6 are
positioned on the i-th horizontal line.
[0032] The scan driver 10 supplies a scan signal of a low level to
the scan lines S1 to Sn during a plurality of sub-frame periods
included in one frame. Here, even-numbered scan lines and
odd-numbered scan lines are driven at a time difference of 1/2
frame. Therefore, the scan driver 10 sequentially supplies a scan
signal to the even-numbered scan lines S2, S4, etc. or the
odd-numbered scan lines S1, S3, etc. during a scan period of each
of the sub-frames.
[0033] The data driver 20 generates data signals using data
supplied from the timing controller 50. The data driver 20 supplies
the generated data signals to the data lines D1 to Dm whenever a
scan signal is supplied. Here, the data signals can be categorized
into a first data signal with which pixels emit light and a second
data signal with which pixels do not emit light.
[0034] The data driver 20 supplies corresponding data signals to
organic light emitting diodes OLEDs positioned on different
horizontal lines for each of the pixels 40. For example, the data
driver 20 supplies a data signal corresponding to the (i+1)-th
horizontal line to pixels 40 which are coupled to an i-th scan line
Si and have organic light emitting diodes OLEDs positioned in the
(i+1)-th horizontal line. The data driver 20 supplies a data signal
corresponding to the i-th horizontal line to pixels 40 which are
coupled to the i-th scan line Si and have organic light emitting
diodes OLED positioned in the i-th horizontal line.
[0035] For example, when a scan signal is supplied to the first
scan line S1, the data driver 20 supplies a data signal
corresponding to a second horizontal line to the first to third
data lines D1 to D3, and supplies a data signal corresponding to a
first horizontal line to the fourth to sixth data lines D4 to
D6.
[0036] The timing controller 50 generates a data driving control
signal DCS and a scan driving control signal SCS corresponding to
synchronization signals supplied from the outside. The data driving
control signal DCS generated from the timing controller 50 is
supplied to the data driver 20, and the scan driving control signal
SCS generated from the timing controller 50 is supplied to the scan
driver 10. The timing controller 50 rearranges data and supplies
the rearranged data to the data driver 20 so that data signals
corresponding to different horizontal lines are supplied from the
data driver 20.
[0037] FIG. 2 shows an embodiment of the pixel circuits 42 shown in
FIG. 1. Hereinafter, one of the pixel circuits 42 will be described
using sub-pixels coupled to the first scan line S1 and the third
data line D3.
[0038] Referring to FIG. 2, the pixel circuit 42 included in each
of the sub-pixels includes a first transistor M1 that is turned on
when a scan signal is supplied to the scan line S1 to provide a
data signal supplied from the data line D3, a storage capacitor Cst
for charging a voltage corresponding to the data signal, and a
second transistor M2 for supplying a current to an organic light
emitting diode OLED(B) and being turned on or off corresponding to
the voltage charged into the storage capacitor Cst.
[0039] A gate electrode of the first transistor M1 is coupled to
the scan line S1, and a first electrode of the first transistor M1
is coupled to the data line D3. A second electrode of the first
transistor M1 is coupled to one terminal of the storage capacitor
Cst. Here, the first electrode of the first transistor M1 is set as
any one of source and drain electrodes, and the second electrode of
the first transistor M1 is set as the other electrode different
from the first electrode. For example, when the first electrode is
set as a source electrode, the second electrode is set as a drain
electrode. When a scan signal (e.g., a low level signal) is
supplied from the scan line S1, the first transistor M1 coupled to
the scan line S1 and the data line D3 is turned on to supply a data
signal supplied from the data line D3 to the storage capacitor Cst.
At this time, a voltage corresponding to the data signal is charged
into the storage capacitor Cst.
[0040] A gate electrode of the second transistor M2 is coupled to
one terminal of the storage capacitor Cst, and a first electrode of
the second transistor M2 is coupled to the other terminal of the
storage capacitor Cst and the first power ELVDD. A second electrode
of the second transistor M2 is coupled to an anode electrode of the
organic light emitting diode OLED(B). The second transistor M2
controls whether or not a current is supplied to the second power
ELVSS via the organic light emitting diode OLED(B) from the first
power ELVDD, and being turned on or off corresponding to a voltage
value stored in the storage capacitor Cst.
[0041] FIGS. 3A and 3B are waveform diagrams showing scan signals
supplied to scan lines.
[0042] Referring to FIGS. 3A and 3B, a scan signal is sequentially
supplied to the odd-numbered scan lines S1, S3, etc. during a scan
period of a sub-frame. When a scan signal is supplied to the
odd-numbered scan lines S1, S3, etc., a data signal is supplied to
pixels 40 coupled to the odd-numbered scan lines S1, S3, etc., and
therefore, the pixels 40 coupled to the odd-numbered scan lines S1,
S3, etc. emit or do not emit light in response to the data
signal.
[0043] For example, when a first data signal is supplied to all the
odd-numbered scan lines S1, S3, etc., light is emitted in a mosaic
form as shown in FIG. 4A. In other words, since organic light
emitting diodes OLEDs of the pixels 40 coupled to the odd-numbered
scan lines S1, S3, etc. are alternately positioned on different
horizontal lines for pixels coupled to a same scan line, light is
emitted in a mosaic form in the display unit 30.
[0044] Thereafter, a scan signal is sequentially supplied to the
even-numbered scan lines S2, S4, . . . during a scan period of a
sub-frame after a time interval of about 1/2 frame. When a scan
signal is supplied to the even-numbered scan lines S2, S4, etc., a
data signal is supplied to pixels 40 coupled to the even-numbered
scan lines S2, S4, etc., and therefore, the pixels 40 coupled to
the even-numbered scan lines S2, S4, etc. emit or do not emit light
in response to the data signal.
[0045] For example, when the first data signal is supplied to all
the even-numbered scan lines S2, S4, etc., light is emitted in a
mosaic form as shown in FIG. 4B. In other words, since organic
light emitting diodes OLEDs of the pixels 40 coupled to the
even-numbered scan lines S2, S4, etc. are positioned on different
horizontal lines for pixels coupled to a same scan line, light is
emitted in a mosaic form in the display unit 30.
[0046] As described above, in the present invention, organic light
emitting diodes OLED of a specific pixel 40 and a pixel 40 adjacent
to the left/right of the specific pixel 40 are arranged to be
positioned on different horizontal lines, so that light is emitted
in a mosaic form. If light is emitted in such a mosaic form, it is
possible to prevent or reduce line-shaped noise from being
generated.
[0047] According to embodiments of the present invention, various
methods may be used to provide a display unit 30 such that a pixel
circuit 42 coupled to the i-th scan line Si is coupled to an
organic light emitting diode OLED positioned in the (i+1)-th
horizontal line. For example, a source/drain metal of the pixel
circuit 42 coupled to the i-th scan line Si may be electrically
coupled (e.g., via a contact hole) to an anode electrode of the
organic light emitting diode OLED positioned in the (i+1)-th
horizontal line.
[0048] While the present invention has been described in connection
with certain exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed embodiments, but, on the
contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended
claims, and equivalents thereof.
* * * * *